In these photos, I'm gluing two loose tone bars for a terrific writer and player named Josh Joffen, who has won multiple times at the famed Kerville Festival.
Typically when gluing loose braces, one has to feel around inside the guitar through the sound hole and attempt to guide the syringe under the loose brace by "feel". Even after getting the needle under the loose brace, it is tough to squeeze in the glue perfectly, as the tip may have gone under all the way and out the other side. You're flying blind so to speak, and it isn't terribly rare to poke yourself! You squeeze the syringe, hope it went where it should, pull out and look in with a mirror to see if all went well. That's how I USED to do it....
With this magical little ultra-low light cam, light filters through the guitar's top to provide illumination...that's right...no internal lights! I can watch real-time as I slide the needle exactly where it needs to be, and see the glue going where it should. It is a precise, clean way to do a perfect job.
You can see in the last photo, the squeeze-out of glue from the clamp!